Interested in participating? Learn about a clinical gene therapy study opportunity.

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STUDY| Clinical Interventional

Enh3ance™ Clinical Gene Therapy Phase 3 Study


12-years of age and older icon

You are 12 years of age or older

Ornithine Transcarbamylase (OTC) Deficiency genetic icon

Diagnosis of late-onset OTC deficiency

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Will comply with study procedures, requirements, inpatient hospitalizations

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Daily treatment with ammonia scavenger(s) medication(s) and/or protein-restricted diet

Why are we doing this study?

DTX301 is an investigational gene therapy that is being developed for the treatment of ornithine transcarbamylase (OTC) deficiency. The purpose of this study is to determine the efficacy and confirm the safety of DTX301 in patients 12 years of age and older with late-onset OTC deficiency.

Enhance Gene Therapy for the Treatment of OTC Deficiency logo
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Additional travel support may be available

Ultragenyx recognizes that your participation in clinical research has an impact on your (and your loved ones’) time. We may provide compensation and travel support for participation in our clinical trials—the details may vary program to program. You will learn more during the consent process.

What is involved?

All participants will receive DTX301, either on Day 1 or at Week 64 (if still eligible).

All patients who receive DTX301 will be offered enrollment in an optional long-term follow-up study.

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  • Up to 6.5 years
  • Screening Period: up to 8 weeks
  • Follow-up Period: about 4 or 5 years, depending on when you receive DTX301
    • This long-term follow-up is important for patients receiving investigational gene therapy products and consistent across gene-therapy trials
  • Primary Efficacy Analysis Period: 15 months
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Study visits

You will have lab tests, clinical assessments, and a review of your electronic study diary at inpatient clinic visits and outpatient visits throughout the study.

The number of visits you will have will depend on when you receive DTX301.

What you can expect?

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Infusion of study and/or placebo medicine into your arm

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Health and disease questionnaires

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Physical exams and vital signs

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Entry and exit interviews

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Cognitive tests

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Electronic diary entries and reviews*

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Blood and urine tests

*Electronic daily diary entries are a key component of understanding a participant’s experience. These involve daily entries for your diet, your OTC medication, and how you are feeling from the start of screening through approximately 2.5 years into the study.
Interested in participating or have questions? Get started

Understanding Gene Therapy

Gene therapy is the introduction, removal, or change of genetic material in the cells of a person. For certain rare genetic diseases, gene therapy offers the potential for treatment that could have a significant impact on the lives of patients. Find out more details, including how gene therapies are designed to work.

Dig Into the Science

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To learn about current and future studies, you only need to fill out the form once.
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Why are we asking this?

As with most clinical trials, certain criteria such as age must be met to determine who can participate.

The date of birth entered should be that of the person who would be enrolled in the trial.
If you are under the age of 18, a parent, care partner, or guardian must fill out this form for you.
Why are we asking this?

Letting us know the Patient's zip code can help us locate clinical trials that are closest to you or your loved one. Many clinical trials are held in hospitals and clinics and may require you to visit a facility in person.

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By submitting this form, you confirm that a diagnosis of OTC has been made by a medical professional.

If you would like to know more about your privacy and the data you submit and data we collect while you are on this website, please see below or visit our privacy policy.

What happens after you submit your information?

Our Patient Enrollment Liaison (PEL) team will contact you by email or phone within one business day to discuss your study eligibility and answer questions.

If you choose to be contacted by email, be sure to check your spam folder for an email from [email protected], if it’s not in your regular inbox.

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Got Questions?

Email our PEL team about current and future medical research opportunities.

Ornithine Transcarbamylase (OTC) Deficiency patient representation Ornithine Transcarbamylase (OTC) Deficiency patient representation

Patient portrayal.

OTC deficiency is the most common urea cycle disorder and leads to increased levels of ammonia. Patients with OTC deficiency may suffer from acute hyperammonemic episodes that can lead to hospitalization, adverse cognitive and neurological effects, and potentially death.

If you are thinking about joining a study, our Patient Enrollment Liaison (PEL) team is here to help. Every member of our PEL team has a robust professional background and clinical expertise and experience to help answer your questions. Your PEL team member will assist in exploring Ultragenyx clinical and non-interventional clinical trials and related sites where you could be considered for enrollment. Your PEL is here to make the process as easy as possible.

To speak with a PEL about current and future medical research opportunities, please email our PEL team at [email protected].

When you voluntarily submit your personal data, Ultragenyx stores and processes this information in an electronic database consistent with our Privacy Policy. Ultragenyx will use this information to contact you to fulfill your request regarding Ultragenyx research opportunities.

Clinical and nonclinical studies provide invaluable information to treat, diagnose, or discover new breakthroughs in treating rare and ultra-rare diseases. By choosing to participate in research, you may help advance treatments, provide crucial insights, and ultimately improve the quality of life for others living with a rare or ultra-rare disease. You might also benefit from learning more about your condition, gain access to specific care, or achieve faster access to treatment. All efforts of participation, big and small, can make a difference.

Ultragenyx is leading the future of rare disease medicine. We leverage our experience, insight, and commitment to help move the rare disease community forward. Our primary goal is to provide medicines to those with limited options, and to help patients face rare disease head on with courage and confidence.

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